1. Field
The field of the invention disclosed herein is plastic injection molding and a device to prevent damage to heater bands, electrical wiring and insulation by molten plastic in an injection molding machine.
2. Description of the Prior Art
Plastic molding is a process using plastic and other materials that when heated can be molded into a variety of products. The molding material is made by heating polymers including thermoplastics, thermosets and elastomers alone or in combination until the molding material is liquid. The liquid molding material may be heated to approximately 400-500° F. and is transported through piping to molds into which the liquid molding material is injected. The molds are then subjected to high pressure in order to conform the molding material to the contours of the mold. The molding material is then allowed to cool until hard at which time it is removed from the mold following which it may undergo further processing to the finished product.
The molten plastic or melt is injected under pressure into a mold through a nozzle which is inserted into the mold opening and through which melt is injected. The nozzle is surrounded by heater bands, electrical wiring and insulation to ensure that the plastic remains molten until injected into the mold. The nozzle remains inside of the injection machine until it is needed to fill a mold with molten plastic. This insures that the nozzle will remain at appropriate temperature to permit the free flow of molten plastic into the mold. When a mold is to be filled with molten plastic, the nozzle is extended from the nozzle housing and into the opening of the mold into which molten plastic is injected. After the molten plastic is injected into the mold, the nozzle is withdrawn into the nozzle housing so that the nozzle will remain at the proper temperature for the next injection of molten plastic into the mold. On occasion, molten plastic will drip or “drool” from the nozzle and enter the nozzle housing where it can damage the heater bands, electrical wiring and insulation. This requires that the injection molding machine be shut down and allowed to cool so that the operator of the injection molding machine can replace the damaged electrical wires, heater bands and/or insulation. This repair operation is costly because the injection molding machine is not operating and repair of the injection molding machine requires a significant expenditure of money for installation of new parts. What is needed in the art is a device which prevents molten plastic or drool escaping from the nozzle from entering the nozzle housing and damaging electrical wiring, heater bands and/or insulation of an injection molding machine.